/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the  "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id$
 */
package wx.xml.xalan.xml.utils;

import java.util.EmptyStackException;

/**
 * Implement a stack of simple integers.
 * <p>
 * %OPT%
 * This is currently based on IntVector, which permits fast acess but pays a
 * heavy recopying penalty if/when its size is increased. If we expect deep
 * stacks, we should consider a version based on ChunkedIntVector.
 *
 * @xsl.usage internal
 */
public class IntStack extends IntVector {

    /**
     * Default constructor.  Note that the default
     * block size is very small, for small lists.
     */
    public IntStack() {
        super();
    }

    /**
     * Construct a IntVector, using the given block size.
     *
     * @param blocksize Size of block to allocate
     */
    public IntStack(int blocksize) {
        super(blocksize);
    }

    /**
     * Copy constructor for IntStack
     *
     * @param v IntStack to copy
     */
    public IntStack(IntStack v) {
        super(v);
    }

    /**
     * Pushes an item onto the top of this stack.
     *
     * @param i the int to be pushed onto this stack.
     * @return the <code>item</code> argument.
     */
    public int push(int i) {

        if ((m_firstFree + 1) >= m_mapSize) {
            m_mapSize += m_blocksize;

            int newMap[] = new int[m_mapSize];

            System.arraycopy(m_map, 0, newMap, 0, m_firstFree + 1);

            m_map = newMap;
        }

        m_map[m_firstFree] = i;

        m_firstFree++;

        return i;
    }

    /**
     * Removes the object at the top of this stack and returns that
     * object as the value of this function.
     *
     * @return The object at the top of this stack.
     */
    public final int pop() {
        return m_map[--m_firstFree];
    }

    /**
     * Quickly pops a number of items from the stack.
     */

    public final void quickPop(int n) {
        m_firstFree -= n;
    }

    /**
     * Looks at the object at the top of this stack without removing it
     * from the stack.
     *
     * @return the object at the top of this stack.
     * @throws EmptyStackException if this stack is empty.
     */
    public final int peek() {
        try {
            return m_map[m_firstFree - 1];
        } catch (ArrayIndexOutOfBoundsException e) {
            throw new EmptyStackException();
        }
    }

    /**
     * Looks at the object at the position the stack counting down n items.
     *
     * @param n The number of items down, indexed from zero.
     * @return the object at n items down.
     * @throws EmptyStackException if this stack is empty.
     */
    public int peek(int n) {
        try {
            return m_map[m_firstFree - (1 + n)];
        } catch (ArrayIndexOutOfBoundsException e) {
            throw new EmptyStackException();
        }
    }

    /**
     * Sets an object at a the top of the statck
     *
     * @param val object to set at the top
     * @throws EmptyStackException if this stack is empty.
     */
    public void setTop(int val) {
        try {
            m_map[m_firstFree - 1] = val;
        } catch (ArrayIndexOutOfBoundsException e) {
            throw new EmptyStackException();
        }
    }

    /**
     * Tests if this stack is empty.
     *
     * @return <code>true</code> if this stack is empty;
     * <code>false</code> otherwise.
     * @since JDK1.0
     */
    public boolean empty() {
        return m_firstFree == 0;
    }

    /**
     * Returns where an object is on this stack.
     *
     * @param o the desired object.
     * @return the distance from the top of the stack where the object is]
     * located; the return value <code>-1</code> indicates that the
     * object is not on the stack.
     * @since JDK1.0
     */
    public int search(int o) {

        int i = lastIndexOf(o);

        if (i >= 0) {
            return size() - i;
        }

        return -1;
    }

    /**
     * Returns clone of current IntStack
     *
     * @return clone of current IntStack
     */
    public Object clone()
        throws CloneNotSupportedException {
        return (IntStack) super.clone();
    }
}
